Art of treating shale and other bituminiferous solids



W. H` HAMPTON ART-OF TREATING SHALE AND OTHER BITUMINIFEROUS SOLIDS Feb.26, 1929.

'i0 complex combination.

, sometimes also with Ilvatcnted Feb. k26, 1929 UNITEDI STATES PATENToFFl WILLIAM HUNTLEY HAMPTON, 0F PORTLAND, O BEGON.

I ABT 0.1!'A TREATIG SHALE AND OTHER BITUMINIFEBOUS SOLIDS.

, Application led December 30, 1921, Serial No. 525,896. Renewed .Tune.28, 1928.

This invention relates to `art of treating ,shale and otherbituminiferous solids; and in particular the invention has -to do'withthe digestion of-shalel lorthe like with a heavy mineral oil, inintimate mixture with a relatively `small' proportion of an addedammonia-liberating base, such as caustic lime, under conditions oftemperature such that complex ni- 'trogen compounds present in thebituminiferous mineral are decomposed at least .to a substantial extentwith liberation of ammonia which can be recovered by suitable meansconcomitantly with recovery of valpable hydrocarbon oil fractionsvaporized during the digestion process,I while at the same time sulfurpresent in reactive condition is bound or fixed and its evolution ashydrogen sulfid and analogous undesirable volatile sulfur compounds issubstantially suppressed. v

In prior copending applications Ser. No.' 318,833, Ifiled August 20,1919, Ser. No. 344,016, filed December 11, 1919, Ser. No. 345,485, filedDecember 17, 1919, Ser. No. 431,188, filed December 16, 1920, I havedisclosedand claimed methods of treating shale and other bituminiferoussolids by digesting the same in finely divided condition and in fini dadmixture with a relatively heavy mineral oil at temperatures preferablyranging from about 600 to 700 F., and recovering hydrocarbon oilfractions vaporized during the digestion, the residual solid mineralmatter remaining after the digestion being lthen most desirablyseparated from the accompanying unvaporized oil and bitumens andsubjected to destructive distillation for recovery of hydrocarbonproducts from such bituminiferous matter as mayhave resisted theliquefyng and resolving act-ion of the digestion oil. The process thusbriefly outlined has proved thoroughly successful but in carrying thesame out in .practice I have now found it especially advantageous tointroduce cer-l tain modifications that achieve and increase theeiciency and economy of the process and otherwise favorably affect theresults at-4 tained. The bitumens present in oil shale and like mineralmatter tain appreciable percentages of nitrogen in Sulfur may also bepresent either in organic or inorganic combination, or both. The Ycombination with hydrogen and carbon, and sulfur, in the form of amidoor amido-sulfur compounds.

Under the conditions of digesting shale practically always con.

nitrogen exists partly inv with oil in accordance Withthe proceduresdisclosed in my prior applications aforesaid, practically none of thenitrogen existing in these complex forms is liberated as ammonia durindigestion. The oil fractions vaporized uring digestion and recovered ascondensates, as well as the residual unvaporized body of oil comprisedin the digested mixture, contain nitrogen compounds; andso does theresidual solid bituminous matter that has resisted or escaped t-hebreaking-down action of the hot oil present in the various oil fractionscause the oils to darken upon' standing. and to deposit but soluble incertain solvents such as alcohol .or benzol. The aforesaid residualsolid bath. The nitrogen compoundsy bituminous matter, upon separationfrom the v i The sulfur content of the original shale or otherbitumini-ferous mineral treated may be present asa constituent of orassociated with bitumen complexes, in which form it is highlydetrimental because itis largely reactive at the digestion temperaturesin question and is evolved as hydrogen sulfid or analogous volatilesulfur compounds when digested at 670o to 700 F. under the conditions ofoperation set forth in my prior applications aforesaid. On the otherhand, sulfur present in the form of iron pyrites, which are carried bysome shales, is not evolved during digestion, iron pyrites beingsubstantially inert at' the temperaturesof digestion. Similarl stablecompounds such as sulfates are not a` ected.

It istherefore a principal object of the present invention to so conductthel digestion treatment of the shale or other bituminous mineral aslargely to break down the nitrogen complexes present and to liberateammonia which can be recovered as a valuable by-product separately fromthe oil fractions vaporized during ing formation and deposition ofresinous substances of the character above mentioned not only in thelighter oil fractions but also in those not vaporized during digestion.Afurther object is to bind or fix reactive sulfur in such mannerhydrogen sulfid or inl other volatile form while at the same timepurifying the hydrocarbon oils produced by the process.

igestion, at the same time avoidi as to suppress its liberation as Otherobjects and advantages of the inven-l I' 70 resinous asphalticsubstances lnsoluble in oils tion will become apparent as 'the'description proceeds. t

The accompanying drawing shows diagrammatically one system of apparatusfor carrying out the novel process.

I have found that the objects of the invention are attained by carryingont the digestion treatment in the presence of a suitable proportion ofa base that will react under the conditions l.of digestion to liberatenitrogen as ammonia, either wholly or to a substantial extent, from thecombinations in which it occurs in the mineral; and that will also reactto bind Areactive sulfur present. Any base capable of reacting to attainthese results, can be utilized Within the broad scope of the presentinvention; but for practical purposes it is found advantageous to employlime as the basic reagent in question, and especially to employ causticlime (CaO), the hydrated form being usually much less effective. Theexact quantity of lime or other basic reagent to be employed in a giveninstance naturally depends upon the proportions of nitrogen and sulfurcontained in the shale in a form which they will react with such base.With the ayerage shale, an addition of 1 to 2 per cent by Weight ofcaustic lime is ordinarily suliicient to accomplish the purposes inview; and it is a very exceptional shale that requires as much as 5 percent to achieve the results sought.

In order to secure the best results in carrying out the invention, it isof great importance to ensure that the caustic lime or other basicreagent is brought into proper reacting relation with the shale. Formaximum effectiveness, both the shale and the lime should be finelypulverized and very intimately 'commingled. This is best accomplished bygrinding the lime and shale together, the' shale having been previously.dried if necessary so that the lime undergoes little or-no hydrationduring the mixing or blending operation. In a particularly desirable Wayof accomplishing this grinding in practice, the shale which has beenpreviously coarsely comminuted by rough crushing, is delivered, togetherwith the necessary amount of added caustic lime, from the bin 1 into theagitating means shown at 4. .The heavy oil to vbe usedr in the digestionmixture is supplied from the tank 2. The mixture is stirredand preheatedto say 300 or 400 F., at which temperatures the shale becomescomparatively soft fand fr iable and is thus in particularly favorablecondition to undergo line grindingin suitable grinding machinery,whereas without Such prt/heating' it-isvery much more dicult topulverize. 'IIhe mixture thus prepared and preheated as described may berun into a ball mill or other suitable grinding device 5 and the solidconstituents of the mixture reduced with comparative ease to a in'e'-"ness such that substantially all of the Solids will pass a 1D0-meshscreen, and in practice it is found desirable that the grinding orpulverizing be continued until 60% or more of t-he solids will pass20G-mesh.' This treatmentachieves a most intimate commixture of the caistic lime with the bituminous mineral, thereby favoringefticientreaction of the lime upon the decomposable nitrogen compounds of themineral during the subsequent kdigestion with liberation of ammonia onthe one hand, and binding of reactive sulfur as cal. cium sulfid (CaS)on the other. Furthermore, fine grinding effectively exposes therefractory bitumens of the shale tothe liquefying and decomposing actionof the heavy digestion oil.

.The oil used for the digestion bath may vary considerably in characterbut it should desirably consist Wholly or in substantial part of oilfractions that 'do not vaporize extensively at or below' 700 F. Instarting operations, this oil may be a stripped oil, a grade of steamcylinder stock known commercially as Congo cylinder oil being suitable,for example. After the process has'been operating for a sufficientperiod,-the digestion oil used may be the heavier fractions of oil de-`rived from the shale itself, said oil being supplied through pipe 28 andtank 3. vIn some cases it is advantageous to employ crude petroleum formaking up the digestion bath. The amount of heavy oil so commingled withthe shale and lime may vary considerably 'depending upon the characterof the particular shale to be treated. In the case of a typical Coloradoshale that normally yields about 30 gallons of oil .per ton by theordinary Scotch distillation method, mixing about one volume of heavyoil with two volumes of crushed shale gives good results.

4Richer vshales require relatively less heavy oil, and leaner shalesmore. The quantity of caustic lime used is advantageously somev Whatinexcess of that theoretically required to effect the desired ammonialiberation and sulfur fixation, especially since the breaking down ofsome ofthe oxygenated vbitumens during the digestion apparentlyeiectshy.- dration of the lime to some extent and thus reduces its activity atthis stage ofthe process, although this hydration is of advantage, at alater stage, as will hereinafter vbe pointed out.

As a rule, the use of t-Wo lper cent by Weight p of caustic lime,figured on the weight Aof the Y shale. 1s sufficient, yand in many'cases onevper 1" 'cent 1s enough.

"Ihe linely ground, mixture prepared as above described andy ofslurry-like consistency, is led through' pipe 6 `intofthe digestor meansshown at 7 and 8. 4The temperature 1f of digestion should be high enoughto bringI about 'the desired liquefaction and breaking down of theshalebitumens in the oil digestion bath.` At the same time thetemperature should not be allowed to go high enough A of from 600o to700o F. being suitable, and the optimum range being about 680 to 700 F.The Huid mass should also be thoroughly agitated continuously throughoutthe digestion to cause constant rubbing of the mineral particles uponeach other and thus expose fresh surfaces to the hot oil bath. It

may be noted here that the action of the hot oil bath on the shalebitumens is not merely a liquefying or solvent action, 'but involves achemical breaking down and decomposition of said bitumens into lighterproducts.- The hea oil added to the shale in making up the dlgestionmixture is also Y in its turn broken down to yield lighter products, dueapparently to chemical interaction between said oil and theshalebitumens under the conditions of digestion. c'

During the digestion, ammonia is liberated and is conducted with the oilvapors and the steam generated in the reaction, through vapor oltakes 9into vapor line 10. No sulfuretted hydrogen is evolved the reactivesulfur being bound by the lime. The oil vapors may be fractionallycondensed as shown at 16 to produce commercialdistillates and theammonia scrubbed out at 17 or otherwise recovered 'according to knownmethods. The unvaporized portion of the digestion mixture is treated, asby centrifuging at 11, 12 and 13, or by dilution with a lighter oil andsedimentation, to separate residual solid matter or tailings, the oilseparated from such tailings being amenable to treatment lfor productionof valuablelubricating oils, for example. When treating the unvaporizedportion of the ldigestion mixture by the centrifugin process justmentioned the continuous ow of wash oils is supplied to the successivecentrifuging units hmeans of the tanks 419, 20, 21 and 24, toget er withthe circulating pumps and flow pipes. In this manner, the heavy oils andother bitumens adhering to the tailings discharged from the separatorsare completely washed out. The

wash oil from the first unit 11'is returned-to the digestor 7; that fromthe third unit 13 is returned through'19 tothe tank 20; while that fromthe-second unit 12 passes through 24 and is separated into its light andheavy constituents by circulating through retort 23, towers 25 and 26,4the respective fractions lbeing returned to the tanks 21 and 3. The

oils, both heavy and light, obtainedas described, have much lesstendency to darken in color, and remain much clearer than when lime isnot added to the mixture. Moreover `they do not 'deposit resinous matterupon standing.

If it is desired to subject the vapors leaving the retort system 7, 8,to further cracking 'to obtain a high yield of gasoline products, thevalves 29 are closed and valve 30 opened and the vapors are deliveredthrough vapor line 14 to suitable superheating coils as described in myprevious application, Serial No. 431,188. The ammonia may similarly berecovered in such a system by the usual scrubbing means. i

It should be noted that carbonates of lime and magnesia, which are oftencarried by shales, do not function usefully in the pressought.

The digestion can be carried on in any suitable digestor as at 7 and 8equipped vwith stirring means 15 and 15, and provided with vaporol'takes 9 leading to a-condenser system 16 and 17. The stirring meansmay adent process and-do not produce the results vantageously serve toadvancethe fluid digestion mixture in a systematic manner from a pointof feed to a point of discharge. Ap-

paratus of this general type being known in the art, rio detaileddescription-thereof v is necessary here. The residual solids or tailingsfrom the digestion having been washed successively with a light oil inthe centrifugal separators =and dried, while passing by means of screwcon- `veyors through the drier 22, may be destructively distilledinretort 23 to obtain further hydrocarbon oils from such bituminousmatter therein as resisted or escaped the action of the hot oil bath,and also to obtain more ammon'iafJlhe character of the tailings is suchthat this can be effected at temperatures ranging from 700 F. initial to900 Fgnal, the final temperature beingobviously much lower than is,required in the Scotch process. a This is because the prior digestionhas rendered the residual bitumens lessrefractory and more amendable toheat treatment. As

regards the ready liberation of ammonia, the partially hydrated'limeserves to supply the.

steam needed at the highertemperatures of destructive distillation toand in theammollt) nia-forming reactions. It isto be noted in thisconnection that as a 'result of the prior digestion the lime is presentin peculiarly intimate commixture with the residual solids and can thusreact most effectively. The distillation is carried to coke, the.hydrocarbons driven .oi being condensed in-towerl `18 and the ammoniarecovered in the scrubber. 17.

The total yield of oils vfrom shale treated bythe method hereinaboveSdescribed is far greater than by the ordinary Scotch destructive`distillation of raw shale, and the amlmonia recovery is also larger andis obtained 'at much lower temperatures.r

y The invention has beendescribe'd more particularly with reference t0treatment '0i bituminous shale, vfor the sake of a concrete volvedfandalso because the invention at present finds its most importantpracticalI application in that field. Moreover, the treatment of shaleis a problem distinct'from the treatment of other bituminiferous solidsoW- ing to the peculiarly refractory and resistant character of thebitumens contained in shale .which has baffled many attempts to extracttively distilled to coke, the process yielding valuable hydrocarbon oilfractions, ammonia and coke by the rational and relativelylow-temperature treatment set forth.

i In the treatment of shale and peat,`where the coky residue fromdestructive .distillation ofthe tailings is usually of too lowrcalorific value for direct use as fuel, there may be a third stage inthe ammonia recovery, as follows: The fixed car` bon of the aforesaidcoky residue, and whatever carbon compounds have survived the Vfinalheating to 900 F., are in highly active condition at the close of thevdistillation and will take fire readily if exposed to air.. Byadmitting such air through inlets or tuyres 24 into contact with thecoky residue in regulated quantity in retort 25, partial combustion maybe effected whereby the temperature is considerably 'raised and furtherammonia liberated and recovered. By proper control of the air admission,a type of producer gas can also be obtained.

lVhat I claim is:

l. In the treatment of solid bituminiferous mineral matter to obtainvaluable products therefrom, the process which comprises heating| suchbituminiferous matter in intimate fluid commixture with anammonia-liberating base and a mineral oil at temperatures notsubstantially exceeding about 700 F., and recovering volatilizedproducts. v

2.v In the treatment of solid bituminiferous mineral matter to obtainvaluable products therefrom, the process which comprises digesting, attemperatures not substantially exceeding about 700-F., suchbituminiferous matter in finely divided condition and in intimate-Huidcommixture with finely divided caustic lime anda mineral oil, andrecovering volatilized products.

3. In the treatment of solid bituminiferous mineral matter to obtainvaluable products therefrom, the process which comprises heating suchbituminiferous matter in intimatefluid commixture With an ammonialiberating base and a mineral oil at temperatures not substantiallyexceeding about 700 F., the

"mixture being agitated kand maintained fluid throughout the digestion,recovering velatilizcd products during digestlompseparatmg residualsolid mattei' from the still fluid mixture after digestion, anddistilling such separated'solid matter to distillate. f 4. 'Ihe processas defined in claim 3 further characterized 'by conducting the cokingdistillation at temperatures from about 700 F. up to about 900 F.

5; The process as defined in claim 3 further characterized by subjectingthe resultant coke, without cooling, to controlled'combustion', andrecovering ammonia from the comh bus'tion gases. condition With lime anda heavy oil, dlgested `as before described, and the tailings destruc- 6.The process of treating solid bituminiferous mineral matter to obtainvaluable products therefrom, which comprises digesting an intimatecommixture of such bituminiferous matter and an ammonia liberatingb..se, both in finely divided condition, in a mineral oil bath,attemperatures above 500 F. but not vsubstantially exceeding 7 00 F., andrecovering volatilized products. erous mineral matter to obtain valuableproducts therefrom, which comprises digesting an intimate fluidcommixture of finely divided fbitmniniferous matter anda finely dividedammonia liberating base with a heavy mineral oil, at temperatures Withinthe approxi- -mate range of from 600 to 700 F., to liberate ammoniafandvvolatilize certain hydrocarbon oil fractions.

8. The process of treat-ing solid bituminiferous mineral matter toobtain valuable products therefrom, which comprises digesting a finelyground mixture of such bituminiferous matter and not exceeding about 5per cent of its Weight of caustic lime with a heavy mineral oil a'ttemperatures approximating 680 to 7 00 F., to liberate ammonia andvolatilize certain' hydrocarbon oil fractions.

9. The process of treating solid bituminiferous matter of the shaletype, to obtain valuable products therefrom, which comprises digestingan intimate mixture of such bitumin-iferous matter and anammonia'liberating base with a mineral oil at temperatures sufficientlyhigh to liberate ammonia but insufiiciently high to cause substantialdeposition of carbon, and also recovering valuable hydrocarbons fromsaid mixture.

10. The process of treating solid bituminiferous matter of the shaletype, to obtain val- The process of treating solid bituminif-v coke Withrecovery of v rial at temperatures Withinihe approximate 'l range offrom 600 to 700 F. with sufficient heavy mineral oil to provide a. fluiddigestion mixture, and recovering both liberated ammonia and volatilizedhydrocarbons.

Y11. The process of treating bituminous shale or the like to obtainvaluable products therefrom, which comprises preparing a mlxture ofpulverized shale or the like with caustic lime and enough heavy mineraloil to ive the mixture a, fluid consistency, d igesting said mixturewith the aid of agitation at temperatures sufficiently high to liquefy asubstantial portion of the shale bitumens but insufficiently high tocause substantial carbon deposition, said mixture remaining fluid duringthe digestion, recovering ammonia liberated and hydrocarbons volatilizedduring digestion, separating residual solid matter from the digestionmixture, and destructively distilling such separated solid matter.

12. The process of vtreating bituminous shale or the like whichcomprises heating and agitating a fluid mixture of inely ground shale,finely ground caustic lime and a heavy mineral oil, at temperaturesabove 500 F. but not substantially exceeding 700 F., and recoveringliberated ammonia and volatilized hydrocarbons.

13. The process as dened in claim 12 in which approximately l to 2 percent of lime is employedin the mixture.

14.-. The process as defined in claim 12 characterized by the furthersteps of destructivel; dist-illing the residual solid matter from t edigestion to obtain coke and further volatile matter including ammonia.

l5. The process of treating solid bituminilerous mineral matter whichcomprises digesting such matter in finely divided condition, attemperatures above 500 F. but insuliiciently high to eect substantialcracking, in admixture with mineral oil and a basic reagent capable ofbinding sulfur present in reactive state under the conditions ofoperation, and collecting a distillate.

16. The process of treating bituminous shale or the like which comprisesdigesting, at temperatures above 500 F. but not substantially higherthan 700 F., a fluid mixture comprising inely divided shale, a heavymineral oil, andv a relatively small proportion of caustic lime, andcollecting distillate from the digestion.

In testimony whereof I hereunto alix my s1gnature.

WILLIAM HUNTLEY HAMPTON.

